Gatifloxacin belongs to fourth generation fluoroquinolone antimicrobial, and it is a broad spectrum antimicrobial which is developed by Japanese Xinlin Inc. and transferred to BMS (Bristol-Myers Squibb) Inc. In December 1999, the oral and intravenous injection formulations of the gatifloxacin are authorized by FDA to market with the trade name of Tequin. Allergan, Inc. has alleged that FDA has authorized 0.3% of ZYMAR™ (gatifloxacin eyedrops) to market in U.S.A. on March 31.
As compared with the preceding three generation quinolone drugs, the gatifloxacin mainly has the following characteristics: first of all, the gatifloxacin exhibits stronger antimicrobial activity against Gram-positive bacteria 2 to 16 times even to 32 times than the first generation to the third generation quinolone drugs; secondly, the gatifloxacin has a very strong inhibition effect on pathogenic bacteria which have tolerance to aminoglycoside, macrolide and other antibiotics, and it does not has crossed drug tolerance with these antibiotics; thirdly, the gatifloxacin has a strong activity against chlamydia, mycoplasma, etc.; at last, since the gatifloxacin introduces methoxyl groups to C8, it overcomes the side effects such as photo-toxicity; thus, the gatifloxacin is more stable in chemical structure, and its safety also is increased,
The Chinese patent application No. CN1448137A (the application No. 03113340.1, the publication date is Oct. 15, 2003) discloses a gatifloxacin gel preparation for external use and eye use, which has gatifloxacin as main component and its supplementary material includes chitosan as gel substrate, iso-osmotic regulator, pH regulator, preservative, injection water, etc. The preparation has gatifloxacin content of 0.1-3 wt % and chitosan content of 0.3-3 wt %. It has obvious anti-infection function and functions of speeding heal of wound, promoting epidermal growth, inhibiting formation of scar tissue, maintaining local medicine density for long term, etc. It is used in treating burns, scalds, skin infection, folliculitis, furunculosis, pustule, trauma infections, eczema infections, gynecological vaginitis, cervicitis and ophthalmic bacillary conjunctivitis, keratitis, corneal ulcer, prevention infections and promoting wound healing after ocular operation, and virulent conjunctivitis, keratitis, aridity conjunctivitis, keratitis, and other diseases. The Chinese patent application No. CN1562030A (the application No. 200410020427.4; the publication date is Jan. 12, 2005) discloses a gatifloxacin ophthalmic gel using HPMC as matrix and the preparation method thereof, which is prepared by using gatifloxacin as active substance, hydrophilic polymer hydroxypropylmethylcellulose (HPMC) as matrix, and adding preservative, iso-osmotic regulator, osmotic regulator, pH regulator and water; the preparation method comprises the steps of dissolving gatifloxacin in water and then adding matrix, preservative, iso-osmotic regulator, osmotic regulator to the mixture with stirring to dissolve them; regulating pH=5-9 with a pH regulator; filtering the resulting solution through a microporous membrane filter, and then adding water to the filer to total volume; the formulation is suitable for treating blepharitis, hordeolum, conjunctivitis, dacryocystisis, keratitis, corneal ulcer, trachoma, and other ocular infections; it is reported that the gel formulation is a flowing semi-solid, which has the advantages of convenient usage, long residence time in eyes; the formulation does not readily run off, so as to maintain an effective treating concentration, and thus it can increase the treating effects; furthermore, the formulation has a low toxicity and stimulatory. However, the above known techniques are still required to be improved in the increase of therapeutic effects, the prolongation of residence time, the decrease of the stimulatory to eye and other aspects.
To sum up, there is still a need for providing a new gatifloxacin ophthalmic formulation, particularly ophthalmic gel, so as to overcome the defects of the existing ophthalmic gatifloxacin formulation.